Referring to FIG. 1, a prior art terminal is illustrated. The prior art terminal has a receptacle. When a plug is inserted into the receptacle, no structure is used to fix the plug. For a long time, it is very possible that the connection between the plug and receptacle will become loose and the power will interrupt so as to affect the operation of the electric device. If electric surge generates, it is possible that important data will lose so as to induce a great lose to users.
Thus the prior art plug is necessary to be improved.